The purpose of this project is to investigate the role of the central nervous system in behavior. In some experiments monkeys (Macaca mulatta) are used to examine the extent to which reflex adjustments of the cardiovascular system can be modified by instrumental cardiovascular conditioning (ICC). Thus far, three procedures have been utilized. In the first, electrical stimulation is administered to localized CNS cardioacceleratory-pressor or cardiodeceleratory-depressor sites, e.g., hypothalamus, and analyses are made to determine if the animal can learn to alter their effects; in a second procedure animals are trained to perform on a food-reinforced exercise task and the ability of the animal to control heart rate during combined exercise and ICC sessions is examined; in a third, pharmacological agents which produce pressor or depressor responses are given during ICC and/or during control periods and baroreflex sensitivity is examined. In other experiments we examine age-related changes in pre- and postsynaptic portions of nigrostriatal pathways of the rat using behavioral and biochemical analytical methods.